Messy eaters: Swabbing prey DNA from the exterior of inconspicuous predators when foraging cannot be observed

Complex coevolutionary relationships among competitors, predators, and prey have shaped taxa diversity, life history strategies, and even the avian migratory patterns we see today. Consequently, accurate documentation of prey selection is often critical for understanding these ecological and evolutionary processes. Conventional diet study methods lack the ability to document the diet of inconspicuous or difficult‐to‐study predators, such as those with large home ranges and those that move vast distances over short amounts of time, leaving gaps in our knowledge of trophic interactions in many systems. Migratory raptors represent one such group of predators where detailed diet studies have been logistically challenging. To address knowledge gaps in the foraging ecology of migrant raptors and provide a broadly applicable tool for the study of enigmatic predators, we developed a minimally invasive method to collect dietary information by swabbing beaks and talons of raptors to collect trace prey DNA. Using previously published COI primers, we were able to isolate and reference gene sequences in an open‐access barcode database to identify prey to species. This method creates a novel avenue to use trace molecular evidence to study prey selection of migrating raptors and will ultimately lead to a better understanding of raptor migration ecology. In addition, this technique has broad applicability and can be used with any wildlife species where even trace amounts of prey debris remain on the exterior of the predator after feeding.     

Genome-wide haploinsufficiency screen reveals a novel role for γ-TuSC in spindle organization and genome stability

How subunit dosage contributes to the assembly and function of multimeric complexes is an important question with implications in understanding biochemical, evolutionary, and disease mechanisms. Toward identifying pathways that are susceptible to decreased gene dosage, we performed a genome-wide screen for haploinsufficient (HI) genes that guard against genome instability in Saccharomyces cerevisiae. This led to the identification of all three genes (SPC97, SPC98, and TUB4) encoding the evolutionarily conserved γ-tubulin small complex (γ-TuSC), which nucleates microtubule assembly. We found that hemizygous γ-TuSC mutants exhibit higher rates of chromosome loss and increases in anaphase spindle length and elongation velocities. Fluorescence microscopy, fluorescence recovery after photobleaching, electron tomography, and model convolution simulation of spc98/+ mutants revealed improper regulation of interpolar (iMT) and kinetochore (kMT) microtubules in anaphase. The underlying cause is likely due to reduced levels of Tub4, as overexpression of TUB4 suppressed the spindle and chromosome segregation defects in spc98/+ mutants. We propose that γ-TuSC is crucial for balanced assembly between iMTs and kMTs for spindle organization and accurate chromosome segregation. Taken together, the results show how gene dosage studies provide critical insights into the assembly and function of multisubunit complexes that may not be revealed by using traditional studies with haploid gene deletion or conditional alleles.     

Relative Prevalence of Grapevine Leafroll-Associated Virus Species in Wine Grape-Growing Regions of California

Some diseases manifest as one characteristic set of symptoms to the host, but can be caused by multiple pathogens. Control treatments based on plant symptoms can make it difficult to effectively manage such diseases, as the biology of the underlying pathogens can vary. Grapevine leafroll disease affects grapes worldwide, and is associated with several viral species in the family Closteroviridae. Whereas some of the viruses associated with this disease are transmitted by insect vectors, others are only graft-transmissible. In three regions of California, we surveyed vineyards containing diseased vines and screened symptomatic plants for all known viral species associated with grapevine leafroll disease. Relative incidence of each virus species differed among the three regions regions, particularly in relation to species with known vectors compared with those only known to be graft-transmitted. In one region, the pathogen population was dominated by species not known to have an insect vector. In contrast, populations in the other surveyed regions were dominated by virus species that are vector-transmissible. Our survey did not detect viruses associated with grapevine leafroll disease at some sites with characteristic disease symptoms. This could be explained either by undescribed genetic diversity among these viruses that prevented detection with available molecular tools at the time the survey was performed, or a misidentification of visual symptoms that may have had other underlying causes. Based on the differences in relative prevalence of each virus species among regions and among vineyards within regions, we expect that region and site-specific management strategies are needed for effective disease control.     

Metallothionein alleviates cardiac dysfunction in streptozotocin-induced diabetes: role of Ca2+ cycling proteins, NADPH oxidase, poly(ADP-Ribose) polymerase and myosin heavy chain isozyme

Diabetic cardiomyopathy contributes to high morbidity and mortality in diabetic populations. It is manifested by compromised ventricular contraction and prolonged relaxation attributable to multiple causative factors including oxidative stress. This study was designed to examine the effect of cardiac overexpression of the heavy metal scavenger metallothionein (MT) on cardiac contractile function, intracellular Ca(2+) cycling proteins, stress-activated signaling molecules and the myosin heavy chain (MHC) isozyme in diabetes. Adult male wild-type (FVB) and MT transgenic mice were made diabetic by a single injection of streptozotocin (STZ). Contractile properties were evaluated in cardiomyocytes including peak shortening (PS), time-to-PS (TPS), time-to-relengthening (TR(90)), maximal velocity of shortening/relengthening (+/-dL/dt) and intracellular Ca(2+) fluorescence. Diabetes significantly depressed PS, +/-dL/dt, prolonged TPS, TR(90) and intracellular Ca(2+) clearing, elevated resting intracellular Ca(2+), reduced caffeine-induced sarcoplasmic reticulum Ca(2+) release and dampened stress tolerance at high stimulus frequencies. MT itself exhibited little effect on myocyte mechanics but it significantly alleviated STZ-induced myocyte contractile dysfunctions. Diabetes enhanced expression of the AT(1) receptor, phospholamban, the p47(phox) NADPH oxidase subunit and poly(ADP-ribose) polymerase (PARP), depressed the level of SERCA2a, Na(+)-Ca(2+) exchanger and triggered a beta-MHC isozyme switch. All of these STZ-induced alterations with the exception of depressed SERCA2a and enhanced phospholamban were reconciled by MT. Collectively, these data suggest a beneficial effect of MT in the therapeutics of diabetic cardiomyopathy, possibly through a mechanism related to NADPH oxidase, PARP and MHC isozyme switch.     

Investigating molecular recognition and biological function at interfaces using piscidins, antimicrobial peptides from fish

We studied amidated and non-amidated piscidins 1 and 3, amphipathic cationic antimicrobial peptides from fish, to characterize functional and structural similarities and differences between these peptides and better understand the structural motifs involved in biological activity and functional diversity among amidated and non-amidated isoforms. Antimicrobial and hemolytic assays were carried out to assess their potency and toxicity, respectively. Site-specific high-resolution solid-state NMR orientational restraints were obtained from (15)N-labeled amidated and non-amidated piscidins 1 and 3 in the presence of hydrated oriented lipid bilayers. Solid-state NMR and circular dichroism results indicate that the peptides are alpha-helical and oriented parallel to the membrane surface. This orientation was expected since peptide-lipid interactions are enhanced at the water-bilayer interface for amphipathic cationic antimicrobial peptides. (15)N solid-state NMR performed on oriented samples demonstrate that piscidin experiences fast, large amplitude backbone motions around an axis parallel to the bilayer normal. Under the conditions tested here, piscidin 1 was confirmed to be more antimicrobially potent than piscidin 3 and antimicrobial activity was not affected by amidation. In light of functional and structural similarities between piscidins 1 and 3, we propose that their topology and fast dynamics are related to their mechanism of action.